Mineral oil, derived from exhaustible natural reserves, is usually employed as a base for bath oils and massage oils, as well as other cosmetics known in the prior art. This application is due mainly to the low cost, safety, availability and emollience foreseen in said oil, which is constituted by a mixture of hydrocarbons obtained from a rigorous purification of the fractions of petroleum distillates.
At present, the use of fossil fuels is considered a serious threat to the atmosphere and to the environment, since the burning thereof emits large amounts of polluting gases and carbon dioxide. Additionally, it is estimated that between 40 and 60 years, natural gas and oil will exhaust worldwide.
Thus, the need to find alternatives that will minimize or replace fossil fuels is vital, due to exhaustion of their reserves or to pollution of the environment and of the atmosphere caused by the burning thereof.
Vegetable oils are a promising alternative for replacing mineral oil used in bath oil and massage oil, since they have many properties and varieties to be exploited, such as high concentration of essential fatty acids, natural moisturizing function and emollience, besides comprising natural bioactives (phytosterols, vitamins, minerals, antioxidants, among others).
The use of oils on the skin began in ancient times as a religious practice, especially in the consecration of priests and kings. The origin of the application of lipids onto the skin goes back to over two millenniums, when they were believed to have benefits in terms of appearance and health of the skin, as well as a barrier against the environment. Cosmetic use of natural oils and fats, which are instable (they oxidize easily) and difficult to emulsify, would not have become so popular if they did not present so many physical benefits, such as emollience, lubrication, moisturizing and occlusiveness, as well as biochemical benefits such as the possible restoration of the damaged skin barrier provided by them. Source: Y. Huy, Bayles Industrial Oil and Fat Products, vol. 5).
Studies and clinical tests aimed overcoming drying-out of the skin are based on the concept that an oily surface or a lipid film would delay the loss of water by evaporation. The importance of bath oils for dry skins is thus explained. Bath oil needs to be applied onto the skin so as to form a thin film and cover as much surface area as possible, without, however, making it oily, and this aspect would be non-attractive to the consumer. The spreadability of the oil should be satisfactory, since said oil should provide a thin film on the skin. A rapid spreading is important, since the area covered by the oil is proportional to its spreadability, and an oil that spread rapidly is considered more attractive for cosmetic reasons (Source: Wilkinsons J. B. and Moore R. J., Harry's Cosmeticology).
At present, the production of body-care products that exhibit emollient properties of vegetable oils is particularly desirable. Vegetable oils can be as emollient as mineral oils and some of them can be even better. In general, vegetable oils do not have the same barrier as mineral oils, since they are polar substances. However, they are capable of penetrating deeper into the horny layer (stratum corneum), which explains the great contribution in terms of softness of these oils. Further, the barrier formed by mineral oils provides reduction of the transsepidemic loss of water and the increase of the moisture of the epidermis, but does not moisturize the skin in an ideal way. From this point of view, the low barrier formed by vegetable oils is considered a benefit. Other reasons for using vegetable oils are the presence of an active ingredient that has physiological function, as well as the fact that unsaturated fatty acids can have beneficial effects for the skin (Source: Connock E., 1998, Cosmetics and Toiletries).
On the other hand, vegetable oils that are in liquid state at room temperature and that comprise a high concentration of unsaturated fatty acids are rapidly oxidized when exposed to the environment (an effect caused by light, temperature and oxygen), which changes the color and odor of the oil, besides entailing the formation of free radicals that cause damages to the cells of the skin and renders the product unacceptable for this use.
The applicant indicates hereinafter relevant documents of the prior art related to the matter of the present invention.
Document U.S. Pat. No. 5,318,777 describes a solvent-extraction process for obtaining an olein with 0% of solids at 20° C. and 4.5% of solids at 10° C., as well as the cosmetic application thereof. The profile of solids of the olein obtained by said process is not suitable for replacing mineral oil in cosmetic products, mainly when it comes to products with a large percentage of this raw material such as emulsions, bath oils and massage oils, among others. This can be verified in the fact that, while carrying out the process, olein will be subjected to a temperature of 10° C. This measure will initiate the formation of crystals with subsequent solidification of the cosmetic product that comprises said olein. This factor is extremely negative and generally associated to quality problems.
Additionally, extraction by solvent is a non-ecologically correct technique, since there may be a contamination of the environment or exhaustion of the natural resources necessary for obtaining the solvents. In this case, the use of hexane is cited, which is obtained from a mineral resource that is expected to exhaust in a few years.
Document U.S. Pat. No. 5,653,988 describes the manufacture of bath oil with 55% of surfactant and 45% of triglycerides. The oils indicated for being used in the compositions foreseen in this document, as for example, soybean oil and/or sunflower oil, have low resistance to oxidation, due to the high concentration of polyunsaturated fatty acids, which makes the product highly susceptible to degradation with the consequent formation of free radicals and unpleasant odor. Due to the possible degradation that this composition would undergo, the addition of antioxidants becomes compulsory and represents a very high cost for the product in question.
Additionally, the high amount of surfactants makes the final product more irritating than the bath oils already known.
Therefore, an objective of the present invention is to provide a vegetable-oil-based cosmetic composition that has advantages preferable to resistance to oxidation and to solidification related to lower financial costs, besides providing excellent cosmetic properties foreseen in the composition of the present invention.